Cita APA (7a ed.)

Santayana, G. (1930). The realm of matter: Book second of Realms of being. Constable.

Cita Chicago Style (17a ed.)

Santayana, George. The Realm of Matter: Book Second of Realms of Being. London: Constable, 1930.

Cita MLA (9a ed.)

Santayana, George. The Realm of Matter: Book Second of Realms of Being. Constable, 1930.